1. Field of the Invention
The present invention relates to the manufacturing of embossing elements and of decorative laminates using inkjet technology.
2. Description of the Related Art
Gravure, offset and flexography are being increasingly replaced for different applications by industrial inkjet printing systems, because of their flexibility in use, such as variable data printing making short production runs and personalized products possible at low cost, and their enhanced reliability, allowing incorporation into production lines.
EP 2865527 A (AGFA GRAPHICS) discloses a method of manufacturing a decorative surface including the steps of: a) impregnating a paper substrate with a thermosetting resin; b) jetting a colour pattern with one or more aqueous inkjet inks including a polymer latex binder on the thermosetting resin impregnated paper; c) drying the one or more aqueous inkjet inks; and d) heat pressing the thermosetting paper carrying the colour pattern into a decorative surface. A major advantage of the described method is that a floor laminate manufacturer (20) can manufacture the decorative layer (34) by inkjet printing in-house. As a consequence, the floor laminate manufacturer (20) is no longer obliged by the décor printer (13) to purchase minimum quantities of décor paper rolls (16) for his warehouse (17) and is no longer dependent on décor paper roll delivery periods set by the décor printer (13) for market introduction of laminates made therewith.
Decorative laminates, like the flooring laminates disclosed by EP 2865527 A (AGFA GRAPHICS), are generally heat pressed at a size of about 2.8 m×2.1 m, which is dictated by the standard dimensions of the heat presses used in that industry. During this heat pressing usually an embossing plate having a relief, e.g. corresponding to the wood grain of a printed decorative wood colour pattern present in the laminate, is employed to deliver decorative panels having a surface relief matching the printed wood grain of the panel. Such embossing plates can be ordered at companies specialized in engraving metal surfaces, but these generally tend to have even longer delivery periods than the décor paper rolls from a décor printer. The latter destroys the advantage of having large variation in the decorative patterns by inkjet. It should be noted that a typical heat press produces about 5 m2 of laminate. A typical room at home is about 25 m2, meaning that in that room each decorative panel will occur about five times, representing an undesirable repetition observable by the customer.
One approach to solve this problem of repetitive decorative panels in a room is to use different heat presses with different embossing plates and then after cutting into panels, mix up the panels in the packaged sets of panels offered for sale. This not only causes a complex sorting and a limitation of flexibility in manufacturing, but one can not be sure which packages will eventually be selected in a store by a customer so that the repetition of decorative panels in a room may not be effectively avoided.
Another approach is to introduce a DVEIR embossing technique for inkjet printed decorative laminates as disclosed by WO 2014/014400 A (FLOOR IPTECH), where an inkjet ink (41) is printed on a foil (40a) and a cavity (37) is pressed into the surface layer (2) of a building panel (1) in register with a decorative print (P). However, the thickness of the foil is a very critical parameter. If a thin foil is used, creases may occur that causes artifacts in the embossed relief or worse a rupture of the foil may occur. If the thickness of the foil is increased, no sharp relief can be realized like that made by a classic embossing plate.
Hence, there is still a need for improved methods of variable embossing when manufacturing decorative laminates.